This invention relates to a direct fuel injected engine and more particularly to an improved direct fuel injected two-cycle engine and to an air supply system for engines.
Although two-cycle engines have considerable advantages because of their simplicity and their high specific output, the substantial overlap in the scavenge and exhaust port openings give rise to problems in maintaining good emission control and good fuel economy. In order to improve the performance of such engines, it has been proposed to employ direct cylinder injection. However, direct cylinder injection in and of itself may not necessarily meet the more stringent demands for fuel economy and emission control.
Therefore, it is desirable to provide an arrangement wherein there may be accomplished some form of stratification in two-cycle engines that employ direct fuel injection. If the charge can be stratified, then the engine can run on a lean burn principal, particularly at low and mid-range conditions. This offers the opportunity of obtaining the necessary emission and fuel economy performance.
It is, therefore, a principal object of this invention to provide an improved direct fuel injected internal combustion engine.
It is a further object of this invention to provide a fuel injected engine wherein stratification can be accomplished.
It is a still further object of this invention to provide a stratified direct injection two-cycle internal combustion engine.
In order to achieve stratification, particularly at low speeds and low loads, it is desirable to introduce excess air into the combustion chamber. If excess air is introduced properly, the stratification can be further improved and, furthermore, lean burn operation is more feasible. However, if the induction system is designed so as to provide excess air, then this excess air may also be existent under wide open load conditions and can deteriorate performance.
It is, therefore, a still further object of this invention to provide an improved arrangement for facilitating the supply of excess air to an engine under certain desired running conditions.
It is a further object of this invention to provide an improved induction system and throttle control arrangement for an engine that will permit the desired amount of air flow under all running conditions so as to accommodate lean burn under some conditions and stoichiometric operation under full speed full load conditions.
It is a further object of the invention to provide an improved method for supplying air to an engine to accommodate lean burn under some running conditions.